The present invention relates to a target-lens-shape measuring device for measuring a target lens shape (a traced outline) of a template (a pattern), a dummy lens, a lens frame of an eyeglass frame, or the like, and an eyeglass-lens processing apparatus having the target-lens-shape measuring device.
In target-lens-shape measuring devices, the target lens shape (the traced outline) is generally measured by detecting the amount of movement of a frame feeler (a stylus) which is brought into contact with a frame groove of a lens frame of an eyeglass frame, or a template feeler (a tracing pin) which is brought into contact with a side surface of a template or dummy lens (hereafter, each of these feelers will be simply referred to as the feeler). A method for detecting the amount of movement of the feeler is carried out in the following manner: A rack-and-pinion mechanism or a mechanism including a wire (or a belt) and pulleys combined together is used to convert the linear movement of the feeler into rotational motion, and the amount of the rotation motion is detected by a rotation detector such as an encoder, thereby obtaining the amount of movement of the feeler.
However, the above-described detection method suffers from a problem in that a deviation may occur between the actual amount of movement of the feeler and the amount of movement of the feeler detected on the basis of an output from the encoder, resulting in an inaccurate result of measurement. Further, the same problem is also applied to the mechanism including the wire (or the belt), and pulleys.
For this reason, calibration is conducted for each device in advance of measurement, and the data obtained through the calibration is stored. However, since the calibration is conducted on the basis of only several pieces of detected data obtained by bringing the feeler into contact with several reference frames differing in size, satisfactory calibration accuracy with respect to linearity cannot be obtained. Further, a special measuring instrument or jig is required to conduct accurate calibration over the entire stroke of the feeler.
In view of the above-described problems, it is an object of the invention to provide a target-lens-shape measuring device which makes it possible to conduct highly accurate calibration with respect to the amount of movement of the feeler over a wide-ranging stroke without the use of a special measuring instrument or jig. Another object of the invention is to provide an eyeglass-lens processing apparatus having such target-lens-shape measuring device.
The present disclosure relates to the subject matter contained in Japanese patent application No. Hei. Hei. 11-286865 (filed on Oct. 7, 1999), which is expressly incorporated herein by reference in its entirety.